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cazksboy
07-26-2012, 03:52 PM
I'm a clock repair hobbyist, and a newbie to machining. I'm in need of a dial indicator to use with my Rivett watchmaker's lathe for the purpose of evaluating TIR of my collet assortment. After cobbling together a workable arrangement with a magnetic base on the lathe bed, I'm realizing that the most efficient use of my available tools would be to mount a dial indicator in the quill of my compound sliderest, since it's moveable along the X, Y and Z axis (the Z axis, "up & down", is moveable due to the brilliant design of the off-center hole in the quill which is rotated within the quill barrel).

I'm having a hard time finding a suitable dial indicator that incorporates all the features I need, and I'd like to ask you guys for a recommendation or two. The dial indicator I'm seeking MUST have all of the following specs:

1. High quality - no cheapie crap.
2. Back plunger style with small contact ball.
3. Half-thousandths resolution (0.0005"). All I can find on the internet seems to be 0.001" for the finest resolution on the dials.
4. 0 - whatever - 0 for the dial layout (I don't know the correct terminology, sorry). I want a zero point in the middle, with "whatever" maximum on the left and right.
5. Mounting post either 1/4" or 3/16" diameter. I'd rather have 3/16" because that's the measurement of my quill's bore, but I also have an alternate quill with 1/4" bore.

Can anyone point me to an indicator with the above specs? Thanks in advance.......

Alistair Hosie
07-26-2012, 04:59 PM
Try Mitutoyo they will fit the bill,there are plenty used in good condition on ebay.or new at high cost:DAlistair

Video Man
07-26-2012, 05:29 PM
Suggest you look at the Mutitoyo 2961F back-plunger .0005 dti, there's one on ebay and a number of links on Google....the one on ebay claims to be new in box....

Dr Stan
07-26-2012, 05:38 PM
Although they are not plunge back I suggest you also consider dial test indicators (DTI's). Brown & Sharpe make excellent ones as does Interapid & Mutitoyo. Examples can be found at http://www.travers.com/skulist.asp?r=s&n=||UserSearch1%3Ddial+test+indicator&q=block+id+33653+and+class+level3+id+29629

and http://www.travers.com/skulist.asp?r=s&n=||UserSearch1%3Ddial+test+indicator&q=block+id+79080+and+class+level3+id+29629

and http://www.travers.com/skulist.asp?r=s&n=||UserSearch1%3Ddial+test+indicator&q=block+id+87261+and+class+level3+id+29629

lazlo
07-26-2012, 05:40 PM
Another vote for the Mitutoyo -- I have three, and I haven't killed one yet :)

Brown & Sharpe/Tesa also make a fantastic dial indicator. You can find both for cheap on Ebay, but I strongly suggest you look for New In Box -- too many shysters with use metrology gear.

cazksboy
07-26-2012, 07:57 PM
Suggest you look at the Mutitoyo 2961F back-plunger .0005 dti, there's one on ebay and a number of links on Google....the one on ebay claims to be new in box....

Thanks guys. Video Man, thanks for the tip. The Mitutoyo 2961F looks pretty good to me (I'm currently using a DTI, and I specifically want to switch over to a back-plunging indicator). One question about the Mitutoyo 2961F.... where does the mounting post go? I don't see one attached, so I'm assuming it's separate. Does it screw onto the indicator's body?

Video Man
07-27-2012, 12:40 AM
I believe the mounting stem surrounds the plunger, or that's how the Mitutoyo back plungers work that I have seen. Stem is probably .375". I have not used this particular indicator....

macona
07-27-2012, 01:17 AM
You dont want an dial indicator, you want a Test Indicator.

Way more useful. I have rarely used a regular dial travel indicator when I got DTI's.

http://www.google.com/#hl=en&gs_nf=1&qe=ZGlhbCB0ZXN0IGluZGljYXRvcg&qesig=E_NS0lYx7CJ51HOkkhUGuw&pkc=AFgZ2tmbXKId3NbEVDyCD13ByURGGKm9M_tiZtjbKyDaB_ 9u0fuvaAOxL6mjIEde8M6RL1SFZyaIq3huPazniW-WCc2i1arZWQ&cp=19&gs_id=4&xhr=t&q=dial+test+indicator&pf=p&output=search&sclient=psy-ab&oq=dial+test+indicator&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&fp=4c9453c8a014c8b0&biw=1558&bih=832

tdmidget
07-27-2012, 01:50 AM
You dont want an dial indicator, you want a Test Indicator.

Way more useful. I have rarely used a regular dial travel indicator when I got DTI's.

http://www.google.com/#hl=en&gs_nf=1&qe=ZGlhbCB0ZXN0IGluZGljYXRvcg&qesig=E_NS0lYx7CJ51HOkkhUGuw&pkc=AFgZ2tmbXKId3NbEVDyCD13ByURGGKm9M_tiZtjbKyDaB_ 9u0fuvaAOxL6mjIEde8M6RL1SFZyaIq3huPazniW-WCc2i1arZWQ&cp=19&gs_id=4&xhr=t&q=dial+test+indicator&pf=p&output=search&sclient=psy-ab&oq=dial+test+indicator&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&fp=4c9453c8a014c8b0&biw=1558&bih=832
READ the OP. He says he wants a back plunger style indicator. He doesn't say why, but does say that is what he wants. While I agree that I would use a Compac dial test indicator He seems to know what he wants or at least thinks he does. He may have a very valid reason.

ogre
07-27-2012, 10:33 AM
I dont know my butt from a whole in the ground on clockworks,but thought id throw it out there. I havea back plunger one that has an attachment that also works like an interipid dial indicater. Dont think it measures to the accuracy you need though,ill have to check. I do not know if these are thest of both worlds or not,just tryin to help. I also had to hand polish the back plunger cause it was not as smooth as i felt it should be for the attachment part to slide across smoothly.

Harvey Melvin Richards
07-27-2012, 10:59 AM
Lufkin made a back plunger ( model 299 and 399) that also can be used as a test indicator, only reads in 0.001" though. I have the Lufkin 299 and a Starrett 196 and it's very rare that I find them to be very useful.

ogre
07-27-2012, 11:33 AM
Harvey i think i agree with you,everytime i think i find a use for it,i always end up going back to my starret last word indicator. Antique but shes beautiful piece of work. But since he wants the back plunger i thought id throw it out there,and i think your right on the accuracy range also.

cazksboy
07-27-2012, 01:26 PM
Thanks for jumping in, everyone. I guess I should clarify a couple of things. My main field is collecting & repairing antique clocks. But I'm trying to acquire some knowledge of basic machining, because often I find that clock repair involves fabricating replacement parts. So I've got a way to go in learning the terminology appropriate for this forum.

What I'm seeking is one of these things, whatever they're called:
http://i215.photobucket.com/albums/cc155/cazbass/DSCF7547.jpg

It's a cheapie (Central). I want to find one of the above indicators (it's called a dial indicator, right?) with a 0-10-0 or 0-20-0 measuring range; I need the dial's increments to be marked in half-thousandths (0.0005") because my tolerances are pretty tight. The contact point should be a little ball tip instead of a convex disc, and ideally I'd like the mounting post to be 3/16" ind diameter, although I could deal with 1/4". If the 1/4" post is detachable, I can turn it down to 1/4". Otherwise I can fabricate an alternate quill (the stock one in my Rivett watchmaker's lathe has a 3/16" bore.

Here's a pic of my sliderest's quill, where I propose to place the indicator (whatever it's called). This pic is of my better-condition sliderest, I have two of them:
http://i215.photobucket.com/albums/cc155/cazbass/DSCF7440.jpg

Here's how I'm currently performing my current task, which is evaluating my collet collection for concentricity:
http://i215.photobucket.com/albums/cc155/cazbass/DSCF7516.jpg

As you can see above, my Mitutoyo DTI is mounted via a magnetic base to the bottom slide. That lets me draw the whole thing along one axis. So I just thought if I had an indicator like I'm imagining then I could just stick the indcator's post in the slidrest quill. Bingo, no magnetic base needed! And all of a sudden I could easily draw the measuring tip toward me/away from me, left/right and also up/down by rotating the quill (the bore is off-center, allowing slight height adjustments...a brilliant design idea from Edward Rivett).

Does an indicator like what I'm seeking exist anywhere at all?

Thanks,
...Doug

loose nut
07-27-2012, 01:33 PM
Goggle Long Island Indicator, they have comparisons about indicators.

Harvey Melvin Richards
07-27-2012, 02:29 PM
Not quite a solution for you, but Starrett makes an adapter that allows you to use 4-48 dial indicator tips on their back plunger indicator. Starrett item # 196R. Starrett back plungers only go to 0.001 AFAK.

http://www.mcmaster.com/#catalog/118/2280/=il9dbl

My back plungers also have removable stems, so they could be turned down from 1/4 to 3/16ths.

Video Man
07-27-2012, 03:18 PM
Suggest you look at the Mutitoyo 2961F back-plunger .0005 dti, there's one on ebay and a number of links on Google....the one on ebay claims to be new in box....

Took a look at the Mutitoyo web site, they have a spec sheet which says this style of indicator can be mounted with optional studs:

Optional Accessories
136567: Holding bar (6mm, L=81mm)
21AAA166: Holding bar (6mm, L=42mm)
136568: Holding bar (8mm, L=81mm)
21AAA168: Holding bar (8mm, L=42mm)
124625: Holding bar (.25 DIA, L=3.19)
21AAA167: Holding bar (.25 DIA, L=1.65)

so I think you could hold it in your mount via one of these....MSC or Grainger might be a source, or probably you could turn one to suit yourself....

Bob Fisher
07-27-2012, 04:29 PM
I don't understand the need for .0005 accuracy on antique clocks,I'm reasonably sure the makers did not have that ability. I repair old clocks, mostly American, and they certainly do not need that degree of accuracy. In fact, the American approach to clockmaking ruined the clock guilds hold on the market. We used mass production and more power to bring the price of a clock to the average man. The typicalAmerican clock will still run, crooked and dry long after the typical French or English movement quits. Not to steal the thread , but just about any indicator should work for your needs, especially for runout type measurements.. Bob.

Arthur.Marks
07-27-2012, 06:06 PM
Okay, let's slow down a little. It sounds like you already have two indicators, although I am unsure what their graduations are. You show two types. The first, "Central" brand, is called a back plunger indicator. First thing to know about it which may be useful is that the tip is replaceable. There are any number of different size and shape points you can install on it. The second, Mitutoyo brand, indicator you show is a "dial test indicator" of the "unibody" style. What the latter means is that the top, back and sometimes the front have a universal dovetail machined onto it. This allows you to attach just about any variety of holding devices or stem diameters. So, for example, yours may have an 8mm straight shank attached in your photo. You can remove this by unscrewing the flat knurled knob by its base. This will loosen the dovetail, and you can slide it off. A 3/16" straight shank replacement should be easy to find. It is also worth noting that the tip (point) can be replaced on this style indicator as well. Typically there is a small flat where the point threads onto the lever stem of the indicator body. A small, circular wrench will allow you to unthread the point at the flats.

Now that those adaptability concerns are covered, I would like to bring attention to one point regarding accurate measuring. Round on round is notoriously inaccurate. As you show above, you have a round indicator point bearing on a round workpiece. A far more accurate method of measurement is to have a flat point bearing on a round workpiece (or visa-versa). The one place this does not hold true, however, is in measuring inner diameters. There, the most accurate method is a round point bearing in a round bore. One way to achieve this arrangement with your current tools is to replace the larger, rounded point on your "Central" back plunger indicator. Source a flat-bottomed point with the correct mounting thread (typically #4-40tpi or M2)

Now, there is one style of indicator that has not been discussed yet. This is commonly referred to as just a "dial indicator". It is a little like a cross between the above two. That said, it is more common than the back-plunger type. It has a rounded dial, often a "lug" on the back, a straight mounting stem of 3/8" or 8mm diameter. Extending down from the mounting stem is a plunger with measuring point. The dial measuring face is perpendicular to the movement of the plunger which takes the measurement.

I had a nice little collection of pictures, but my other computer just crashed for the third time today :( Hence, I'm a little handicapped on the one I'm writing this response from. Maybe I can upload them later today... In the meantime, to address your literal question---for back plunger indicators, two very good models are the one made by Starrett (USA) and another which is made by Kafer (German). The retailer Long Island Indicator already mentioned sells the latter. All of the usual distributors should be have the Starrett available. For dial test indicators, there are almost too many to mention. Generally, though, the Brown & Sharpe BesTest indicator or the Interapid brand are usual suspects. The Starrett "Last Word" also has its devoted fans. For dial indicators, I like Mercer, but there are a wide number of equivalently good brand alternatives.

I hope this has at least clarified some terminology for you. I would expect there to be a convenient mounting option for just about any design of test instrument to fit your Rivett 3/16" boring bar tool post.

Harvey Melvin Richards
07-27-2012, 06:19 PM
Okay, let's slow down a little. It sounds like you already have two indicators, although I am unsure what their graduations are. You show two types. The first, "Central" brand, is called a back plunger indicator. First thing to know about it which may be useful is that the tip is replaceable. There are any number of different size and shape points you can install on it. The second, Mitutoyo brand, indicator you show is a "dial test indicator" of the "unibody" style. What the latter means is that the top, back and sometimes the front have a universal dovetail machined onto it. This allows you to attach just about any variety of holding devices or stem diameters. So, for example, yours may have an 8mm straight shank attached in your photo. You can remove this by unscrewing the flat knurled knob by its base. This will loosen the dovetail, and you can slide it off. A 3/16" straight shank replacement should be easy to find. It is also worth noting that the tip (point) can be replaced on this style indicator as well. Typically there is a small flat where the point threads onto the lever stem of the indicator body. A small, circular wrench will allow you to unthread the point at the flats.



Semantics here, but I would argue that a test indicator has a tip that rotates about a central pivot. I have numerous test indicators that don't have dovetails, like Starrett Last Word, Jem indicators and lots of the older versions that don't have a clock like face.

Also finding tips for back plunger indicators can be difficult, unless you can find an adapter tip like I mentioned in thread # 15. Not all back plunger's have the same tip threads.

Arthur.Marks
07-27-2012, 06:47 PM
Yes, I agree. One trouble often in these threads is terminology. Even highly regarded reference texts can disagree. When I referred to "the top, back and sometimes front have a universal dovetail machined onto it," I was referring to the "unibody" design specifically. I might be wrong, but I understand that term to mean as much.

I've never owned a back plunger indicator but sometimes wonder why they seem to be less prevalent. I was unaware they use non-standard threads on the contact points. Thank you for the correction.

cazksboy
07-28-2012, 12:09 AM
Okay, let's slow down a little. It sounds like you already have two indicators, although I am unsure what their graduations are. You show two types. The first, "Central" brand, is called a back plunger indicator. First thing to know about it which may be useful is that the tip is replaceable. There are any number of different size and shape points you can install on it. The second, Mitutoyo brand, indicator you show is a "dial test indicator" of the "unibody" style. What the latter means is that the top, back and sometimes the front have a universal dovetail machined onto it. This allows you to attach just about any variety of holding devices or stem diameters. So, for example, yours may have an 8mm straight shank attached in your photo. You can remove this by unscrewing the flat knurled knob by its base. This will loosen the dovetail, and you can slide it off. A 3/16" straight shank replacement should be easy to find. It is also worth noting that the tip (point) can be replaced on this style indicator as well. Typically there is a small flat where the point threads onto the lever stem of the indicator body. A small, circular wrench will allow you to unthread the point at the flats.

Now that those adaptability concerns are covered, I would like to bring attention to one point regarding accurate measuring. Round on round is notoriously inaccurate. As you show above, you have a round indicator point bearing on a round workpiece. A far more accurate method of measurement is to have a flat point bearing on a round workpiece (or visa-versa). The one place this does not hold true, however, is in measuring inner diameters. There, the most accurate method is a round point bearing in a round bore. One way to achieve this arrangement with your current tools is to replace the larger, rounded point on your "Central" back plunger indicator. Source a flat-bottomed point with the correct mounting thread (typically #4-40tpi or M2)

Now, there is one style of indicator that has not been discussed yet. This is commonly referred to as just a "dial indicator". It is a little like a cross between the above two. That said, it is more common than the back-plunger type. It has a rounded dial, often a "lug" on the back, a straight mounting stem of 3/8" or 8mm diameter. Extending down from the mounting stem is a plunger with measuring point. The dial measuring face is perpendicular to the movement of the plunger which takes the measurement.

I had a nice little collection of pictures, but my other computer just crashed for the third time today :( Hence, I'm a little handicapped on the one I'm writing this response from. Maybe I can upload them later today... In the meantime, to address your literal question---for back plunger indicators, two very good models are the one made by Starrett (USA) and another which is made by Kafer (German). The retailer Long Island Indicator already mentioned sells the latter. All of the usual distributors should be have the Starrett available. For dial test indicators, there are almost too many to mention. Generally, though, the Brown & Sharpe BesTest indicator or the Interapid brand are usual suspects. The Starrett "Last Word" also has its devoted fans. For dial indicators, I like Mercer, but there are a wide number of equivalently good brand alternatives.

I hope this has at least clarified some terminology for you. I would expect there to be a convenient mounting option for just about any design of test instrument to fit your Rivett 3/16" boring bar tool post.

Hi Arthur, pleased to make your acquaintance. Your post was really enlightening - you cleared up some terminology for me! Also, I cannot believe I never thought to just look for a 3/16" dovetailed shank - that would be an easy solution! Why didn't I think of that? :confused: The shank depicted in my third photo measures 6mm, and I have another that measures 10mm but I rarely use that one.

Your point is well taken, regarding using round-against-round (excepting inside surfaces, of course). I more or less understood that to be an issue at the beginning of this project (I have over 150 collets to evaluate for concentricity!). So what I did with my current setup (again, depicted in my 3rd photo) is begin by measuring my smallest collet with an 0.013" gauge pin inserted. Before I locked down my DTI in place, I sighted down the top of an 18" Home Depot bubble level and didn't quit twiddling with my mag base & arms until I was certain that the ball tip was centered horizontally on the gauge pin. It took me about 20 minutes, but I figured I'd be glad later to make sure my readings aren't off due to incorrect contact - especially with so many collets to test. Anyway, once I got the smallest gauge pin lined up with the ball tip, I just proceeded down the line to the largest size, knowing they'd all keep the same center.

I'll also check to see if an alternate tip is available for my Central back-plunger. I've already contacted them once and found their customer service pretty darned good.

If anyone wonders - I probably could get away with an .001" indicator dial - but I repair Viennese regulators and some watch work as well. But even if I didn't, I view the pursuit of precision as an attainable goal. So for a few extra bucks, why not invest in a better tool? I could be wrong.

Thanks again...
...Doug